The invention concerns a linear guide comprising a guide housing configured as a profiled support that is an extrusion molded profile made of aluminium, and at least one guide rail fixed therein, one or more guide carriages being supported for longitudinal displacement on the guide rail while being connected to a running carriage that is situated partly outside the housing and extends through a longitudinal opening into the housing, the linear guide comprising within the housing, a drive for the longitudinal displacement of the guide carriage and of the running carriage, said drive being configured as an electromotor with one motor component arranged in the guide housing and one motor component arranged in the running carriage.
Driven linear guides have been hitherto used mainly in the field of handling. New markets and uses open up, above all, when there is a demand for high displacement dynamics coupled with high positioning exactitude (overshoot-free positioning), simple mounting in existing structures or structural profiles, or for cantilevered installation. A ball screw drive does indeed achieve the required positioning exactitude but compared to a belt-driven linear guide, the achievable speed of the running carriage is limited to low values due to the limit rotational speed of the bearing and the critical speed of rotation of the spindle that is strongly length-dependent.
Conversely, with belt-driven linear guides, high speeds of displacement are achieved but only a poor positioning exactitude. The drawback of the low rigidity of this drive concept compared to a ball screw drive becomes apparent at high acceleration and a great number of cycles. This manifests itself in an overshooting of the targeted position by the running carriage.
A linear guide unit is known from the document DE 196 36 270 A1. For displacing the running carriage on the guide rail in the longitudinal direction thereof, this linear guide possesses a pneumatic linear drive that surrounds a cylinder space of elliptical cross-section arranged in a bottom wall of the guide housing. A piston is guided in this space and each of its two ends is connected to one side of the drive. Each side of the drive leads through a deflecting roller to one end of the running carriage. A differing air pressure loading of the working chambers on either side of the piston results in a displacement of the piston and thus in a displacement of the running carriage in the opposite direction. The drawback of such a linear guide equipped with a pneumatic drive is its very complex structure.
The document FR 2 704 993 shows a linear guide equipped with an electric linear drive in whose profiled support made, for example, of aluminium, several driven carriages that are mechanically independent of each other can roll through rollers on one common rail. The rail is integrally formed on the profiled support. A carriage configured as a vertical plate extends through aligned slots of the rail and of the profiled support to the outside. On the ends of the running carriage situated on the outside, it is possible, for instance, to hang curtains or sliding doors that have to be moved. Measures for closing the free regions of the slots of the profiled support that are situated between the successive carriages are not provided in this linear guide.
The object of the invention is to create a compact linear bearing of a simple structure that can be economically manufactured.
The invention achieves this object by the fact that the longitudinal opening is closed by a cover strip made of anti-corrosive magnetic steel for which permanent magnet strips are inserted into grooves of the guide housing. By the use of an extrusion molded aluminium profile as a guide housing, a combination of a driven linear guide unit with a weight-optimized, inherently rigid support profile is obtained.
The primary motor component may be arranged in the running carriage and the secondary motor component in the guide housing. The longitudinal opening can be closed by a cover strip of anti-corrosive magnetic steel for which permanent magnet strips can be inserted into grooves of the guide housing.
Besides a drawn support profile of aluminium with one or more integrated profiled rails, the linear guide of the invention may contain the following components: a length measuring system, one or more running carriages with guide carriages, a drive in the form of a linear motor surrounded by the support profile, two end plates and a cover in the form of a corrosion-resistant steel strip.